Question

The number of photon of light having wavelength 100 nm which can provide 1 J energy is nearly:

• A. ${10}^7$ photons
• B. $5\times {10}^{18}$ photons
• C. $5\times {10}^{17}$ photons
• D. $5\times {10}^7$ photons

Answer 1

The correct option is C $5\times {10}^{17}$ photons

We know that:
$E=\frac{nhc}{\lambda }$
$n=\frac{E\lambda }{hc}$
$=\frac{1\times 100\times {10}^{-9}}{6.626\times {10}^{-34}\times 3\times {10}^8}=5\times {10}^{17}$